 Now, we talked about the energy flow diagram and we talked about the overall global energy use. We would like to see how does India compare with the world and what are the expected growth rates in the Indian context. So what I would, I suggested to you that you should actually look at different countries and try to do the energy balance. We can do the same thing for India. We have a table which gives you the indigenous, what is the amount of production of coal, oil, natural gas, what kind of, what are the imports, exports and the stock changes and then you can get the primary commodities. Some of them are being transformed into secondary commodities. For instance, coal is being transformed to electricity and even in electricity we are importing and exporting, we are importing electricity from Nepal and we may be exporting again to some of our neighbors, then may be stock changes and then there is a final use. So this is what is there, there is a, in the International Energy Agency there is a Energy Statistics Manual and with that you can look at the database and you can actually work out this for any country that you want and that will give you also a sense of the calculation, a sense of these energy flow diagrams and a relative sense of magnitude, which is how important is hydro, how important is coal, how much of the energy is imported for that country and I would encourage you to do this on your own so that you get a sense of the overall energy. So when we talk about the energy balance, you will find for instance if you are trying to do this for India we would like to see in a year how much coal are we using, how much oil, tons of oil, tons of coal or barrels of oil and then in the case of the natural gas it is often expressed as normal meter cube or standard meter cube, electricity will be in kilowatt hour or million units and then for a physical, for a certain amount of coal we will measure the energy content by either the gross calorific value or higher heating value or the net calorific value based on the fuel composition and then we can convert it also into coal equivalent, oil equivalent that kind of thing. So typically when you look at an Indian balance we take Indian coal has an average energy content which is lower than that of international South African or Australian coal and it is right now the average may be of the order of little less than 5000 kilocalories per kg, 4500 you multiply that by 4.18 kilojoules and you get 18.8 mega joules per kg and oil has a greater calorific value per kg, it is about 41.8 mega joules per kg and natural gas is of that same order of magnitude. In the case of nuclear and hydro it is very difficult to talk about the amount of flow of water but what we know is, we know the generation from hydro plants and we work backwards using the efficiency. So hydro efficiency, plant efficiencies of the order of 85 percent, nuclear of 25 percent and then you can get what is the energy content. So some of the terms that we may want to look at when we do these overall balances, one is the plant load factor. Plant load factor of a plant is the actual generation of a plant over a period which may be a day or a month or a year divided by the maximum possible generation if it is operated continuously at the rated or the design value. So typically what happens in these plants is that the plant would like to operate at high plant load factor. Why is that? That is because whatever investment you have you would like to recover it over a larger number of units. So your electricity would be cheaper if you have higher plant load factors but the plant load factor will be dictated by the fact that you know you cannot just supply electricity to the grid. There has to be a demand for that electricity. So that supply demand matching is one of the factors when you look at the electricity system but so plant load factor is one of the things. In every power plant there is an auxiliary consumption that means in a coal based power plant you will find that there are fans and there are pumps and these consume electricity. So of the electricity which is being generated some part is being used internally inside the plant itself that is the auxiliary consumption and so what we often do is we can specify the output of a power plant in terms of the gross power output or the net power output. In the Indian power system we specify it usually by the gross power output. In the Europeans and US often talk about it in terms of net power output and then the gross power output minus whatever is being used internally becomes the net power. So the auxiliary consumption percentage is the auxiliary consumption into 100 divided by the net power output. So if you look at these terms let us do a simple calculation. So if we look at a thermal power plant which is rated at 500 megawatt gross it has 9 percent auxiliary consumption and has an annual PLF of 80 percent. So we want to calculate the annual generation in megawatt hours and in million units and in gigajoules. And the next part of the question is if the plant has an efficiency of 38 percent calculate the input energy supplied to the plant we can do this in terms of megajoules, petajoules, terajoules in joules basically and if the input energy use this coal calculate the amount of coal used. So let us solve this problem. Let us look at this is a 500 megawatt plant and 500 megawatt this is a unit of power. So if we look at 500 megawatts in an hour the plant generates if it is operating at its rated load it will generate 500 megawatt hours. In a day it will generate 500 into 24 and in a year the maximum that it can generate if operating at its rated load is 500 into 24 into 365 megawatt hour. Now this turns out to be you can do the number you will find that this is 438 into 10 raise to 4 megawatt hour. Now let us see it is also been told that let us calculate this in million units. Million units is million kilowatt hour. One megawatt hour is 10 raise to 3 kilowatt hour. So we are talking of million units means 10 raise to 6. So then this is going to be equal to 438 0 into 10 raise to 6 million kilowatt hour also known as an MU and you will find in many of the reports all the electricity data is given in MUs which is this. Sometimes you will find in the larger scale reports that instead of million units we also talk in terms of billion units. So if this was billion units this would be 4.38 billion kilowatt hour. So we did that first part. Now we want to see you see we have 9% auxiliary consumption. So this is the gross power output. If it is operating continuously it is the maximum. We have a plant load factor of 80%. So the plant load factor PLF is 0.8. This will be the actual generation by maximum possible generation. So the actual generation is sorry this should be 438 0 million kilowatt hour 438 0 MU. This is 438 0 MUs. And so the actual generation is 0.8 into 438 0 million units which is you can multiply it and you will get 3504 MUs. Now this is the gross generation, gross actual generation. If you want to convert this into gigajoules this will be now 1. If we look at this, this is 3504 into 10 raise to 6 kilowatt hours. 1 kilowatt hour is 3600 kilojoules. This is in kilojoules. And if we are multiplying getting this in gigajoules we have to divide this by remember gigajoules 10 raise to 9. So it is this is so many gigajoules. And so that is this is the kind of calculation actually we can even the number is quite high. And instead of gigajoules we can put this in terms of terajoules divided by another 10 raise to 6 and you will see that you get an answer of 12600 sorry 126144 terajoules, can check this number, okay. Now let us look at this was the gross generation. We were talking in terms of the auxiliary consumption. So if we look at a power plant we have an input and we have a gross generation. This gross generation is 3504 mUs out of which we have an auxiliary consumption a being used and this net which we get is 3504 minus a. So let us calculate we are told that 9% is the auxiliary consumption which means a divided by the net output which is 3504 minus a is equal to 9 by 100. And when you calculate this you will find that 8 turns out to be 346.5 mUs. So the other thing that we have to calculate we have to calculate the energy input in terms of input energy and the annual amount of coal used. So if you look at the input energy we already calculated that the output is 126144 into 10 raise to 12 joules or 10 raise to 9 kilojoules and the energy input will be this. This is the total output. This has to be divided by the efficiency. So when you calculate this you will find that this comes to 33196 terajoules it is a large number. 500 megawatt plant almost operating at its full load continuously for a year. So let us see now what does this mean in terms of the amount of coal used. So this energy is supplied by the coal. So we will need to know how much is the amount of energy per unit of coal and if you see we are talking of a calorific value of 4500 kilocalories per kg into 4.18. So this is so many kilojoules per kg of coal which is 18810 kilojoules per kg. So what we need to do is we take this number that we have, the energy input that we are providing 31, 300196 into 10 raise to 9 kilojoules divided by 18810. This is per, this is now kg of coal per year that is a very, kg is a small unit. So let us make it into tons so we divide it by 10 raise to 3 and let us see how many million tons. So we will divide it again by 10 raise to 6. So this is now million tons of coal per year. So then when you look at this if you divide this you will get 1.76 million tons of coal per year. We could also divide the amount of coal per unit of electricity that we are generating. Again we can decide whether it is for gross or net and when you do that you find that we are using about 0.5 kg of coal per kilowatt hour. We will come back to this when we talk about the environment and other things. But here this was to just show you one simple calculation when we think in terms of energy and power and we look at a power plant. Let us go back to our main topic and using this we can actually build up a total energy balance equation. Remember we were talking in terms of, in extra joules for India you will find that the largest chunk of our energy supply comes from coal and we get a reasonable amount of coal in terms of imports. In terms of oil also is a major chunk of our energy supply. In the oil the bulk of the oil is coming from imports. So if you look at the total primary energy supply of 47 extra joules you will find that this then goes and we can see a large chunk of the energy is going to the power sector. And then in the power sector there are conversion losses and transmission and distribution and auxiliary losses and then you have the electricity which is going to different sectors. One of the major sectors is the industrial sector for electricity and then is the residential sector and then the rest the commercial. And we have a reasonable amount of biomass which is being used in our energy supply. Most of it is being used in the traditionally in the residential sector for cooking with very low efficiency. So this is like a psyche diagram which gives you an sort of overall idea of the energy situation in the country. Let us also do a simple calculation of India versus the world. We are a population we have a population of about 1.3 billion as compared to the world 7.4 billion and we are one of the largest countries in the world. You will see that on a per person basis the GDP is about a little less than half of the world average and this is done on a per chasing power parity basis later on in this course we will talk about market exchange rate and purchasing power parity. If we look at the energy inputs we can see the primary energy used is 36 exajoules and for the world it is about 576 exajoules and the energy used per person again we on an average the energy used per person is significantly lower than the world average may be about a third of that. And similarly if you look at the electricity used 920 kilowatt per person per year as compared to 3000. This obviously means that on a per capita basis are CO2 emissions are significantly lower than the world average CO2 per unit of GDP is of course slightly higher and we will come back to this when we talk about the kaya identity and other factors. So when we look at different energy systems there are many different pathways for end users. So we you can look at we talked about the energy flow diagram and when we talk about the energy flow diagram we are looking at different primary energy sources whether it is solar, biomass, wind, small hydro, geothermal, grid electricity and this many of these can come into creating electricity and then that goes into the different kinds of end users like space cooling, space heating, water heating, cooking, lighting and there are many different ways in which we can configure energy systems. So with this if we look at the overall summing up of what we have discussed today we talked about an energy flow diagram and we saw how we move from primary to secondary and to the final energy to the energy end use. We then took that concept to create an energy balance diagram for a region. We looked at what factors affect the overall energy use. We looked at different units of power and energy and their conversion we talked about a 500 megawatt power plant and did a simple calculation. If you look at the energy use pattern we are talking of exponential unbounded growth and that itself may not be sustainable and that is the issue that we will talk about when we talk about energy and environment. There is a disparity between developed and developing countries and this again is something which we will touch upon in the course when we talk in terms of inequality, measures of inequality and see how to aggregate and look at inequality and their impacts both in terms of income as well as in terms of energy. Drawing up aggregate energy balances we talked about level of aggregation which is basically for the country as a whole or the world as a whole and we were talking of physical and energy units. The goal with what we have done today and with the references you can develop an energy balance for a region and we would encourage you to look at one country and look at an energy balance and look at the trends of that energy balance in that country and this will help you get some insights on the energy systems for that country. So the question that I leave you with is what are the drivers for energy systems? So we saw that population is a driver, the income and the increase, the affluence is a driver for energy systems and in addition to this there are other drivers and we will see that the environment is one of the major drivers for energy systems and that will be the next theme that we talk about. In this course we will look at the energy systems, we will look at the resources for energy supply, we will look at how to allocate and them optimally and we will look at economics and we will look at environment. So we will basically blend energy, resources, economics and environment to get a complete perspective and give you the tools and techniques for you to be able to analyze different decisions in the energy sector. These are some of the references which we have used and I would encourage you to look at the global energy assessment. The first chapter provides the basics and that will be, those will give you a lot of the inputs that will be required later on in the course. There are also many different sources and that is the International Energy Agency and the World Energy Outlook where you will have a large number of numbers and scenarios but we would like you to be able to go behind these numbers and to be able to do the analysis so that you can understand what is happening in the system. So with this we will conclude this lecture. Thank you.